Why do different people, professions, and even word processing apps have different views on putting one or two spaces between sentences? Because typewriters made the spaces hard to distinguish. But it's 2010, one writer argues, and time to single-space up.

Farhad Manjoo details the history of the single-versus-double debate at Slate, and makes a compelling argument for sticking to single spaces—and avoiding Courier fonts. Single-spaced sentences were the norm, he writes, up until bad typewriter design crept into mid-20th-century life:

The problem with typewriters was that they used monospaced type-that is, every character occupied an equal amount of horizontal space. This bucked a long tradition of proportional typesetting, in which skinny characters (like I or 1) were given less space than fat ones (like W or M). Monospaced type gives you text that looks "loose" and uneven; there's a lot of white space between characters and words, so it's more difficult to spot the spaces between sentences immediately. Hence the adoption of the two-space rule-on a typewriter, an extra space after a sentence makes text easier to read. Here's the thing, though: Monospaced fonts went out in the 1970s. First electric typewriters and then computers began to offer people ways to create text using proportional fonts. Today nearly every font on your PC is proportional. (Courier is the one major exception.) Because we've all switched to modern fonts, adding two spaces after a period no longer enhances readability, typographers say. It diminishes it.

We're definitely on Team Single-Space here at Lifehacker—our blogging software actually auto-corrects a double-space into a single. Megan McArdle at The Atlantic makes a compelling argument for her beloved double-space, and now we're wondering: How do you space, and why?